Sperm don’t like a cigarette before sex

By William Atkins
Sunday, 03 June 2007 19:05

Science - Health

Lead investigator Carole L. Yauk, of Health Canada’s Environmental and Occupational Toxicology Division, states that smoking in men can permanently change the DNA of sperm cells, which causes irreversible changes in the genetic composition of their offspring.

DNA, or deoxyribonucleic acid, is the substance—specifically, a nucleic acid molecule with a twisted double strand double helix form—that carries the genetic information for humans and other living organisms from one generation to the next.

Tauk and her collaborators from Health Canada and McMaster University have their results (“Mainstream Tobacco Smoke Causes Paternal Germ-Line DNA Mutation”) published in this week’s issue of the scientific journal Cancer Research (2007 67: 5103-5106). Martin R. Stämpfli led the team from McMaster University. Other collaborators include M. Lynn Berndt, Andrew Williams, Andrea Rowan-Carroll, and George R. Douglas.

The article’s abstract appears at the Cancer Research website.

Within their study, the researchers used spermatogonial stem cells (those stem cells that constantly produce sperm in all mammals) and exposed them to cigarette smoke for six or 12 weeks. The mice were exposed to two cigarettes per day, which is equivalent to the amount taken in by an average human that smokes.

A control group was not exposed to the smoke. Their results show that the mice exposed to the smoke—for 12 weeks—were 1.7 times more likely to have DNA mutations than the mice not exposed to smoke. The mice exposed for six weeks were 1.4 times more likely to have mutations than the control group of mice.

They conclude that the longer the male mice were exposed to cigarette smoke the more damage that accumulates within sperm and the more likely genetic mutations will occur in offspring.

Tauk emphasized the fact that it has been previously known that mothers who smoke during their pregnancies can harm their fetuses. This study adds more evidence to the detrimental effects of cigarette smoke on offspring from men smoking even before their offspring are produced.

Yauk and her collaborators plan to learn more about this relationship as they study how the modified DNA reacts in the first-generation and second-generation offspring of the studied mice, both with respect to firsthand and secondhand smoke.